which compound has a nonpolar bond in which the electrons are shared equally

HESI A2

Chemistry Hesi A2

1. Which compound has a nonpolar bond in which the electrons are shared equally?

A. H₂O
B. NH₃
C. Cl₂
D. CH₄

Correct answer: D

Rationale: The compound CH₄, methane, has a nonpolar bond where carbon and hydrogen share electrons equally. This occurs because carbon and hydrogen have similar electronegativities, meaning they have equal abilities to attract shared electrons. Consequently, a nonpolar covalent bond is formed due to the balanced sharing of electrons between these atoms. Choices A, B, and C do not have nonpolar bonds with electrons shared equally. In H₂O (water), there are polar covalent bonds due to the difference in electronegativity between hydrogen and oxygen. In NH₃ (ammonia), the nitrogen-hydrogen bonds are polar because of the electronegativity difference. In Cl₂ (chlorine gas), the Cl-Cl bond is nonpolar, but the question specifies a compound, not an element, and chlorine does not share its electrons equally with another element in a compound.

2. What are proteins made up of?

A. Fatty acids
B. Amino acids
C. Nucleotides
D. Sugars

Correct answer: B

Rationale: Proteins are made up of amino acids. Amino acids are the building blocks of proteins, essential for various biological processes in the body such as enzyme function, transport, and structural support. Fatty acids (Choice A) are components of lipids, not proteins. Nucleotides (Choice C) are the building blocks of nucleic acids like DNA and RNA, not proteins. Sugars (Choice D) are carbohydrates and are not the primary components of proteins.

3. In which state of matter are particles packed tightly together in a fixed position?

A. Liquid
B. Solid
C. Gas
D. Plasma

Correct answer: B

Rationale: In a 'solid' state, particles are tightly packed in fixed positions, maintaining a definite shape and volume. This arrangement allows solids to maintain a rigid structure. Liquids have particles that are close together but can move past each other, giving them the ability to flow and take the shape of their container. Gases have particles that are far apart and move freely, leading to their ability to expand to fill any container. Plasma is an ionized gas where particles have high energy levels and are not packed tightly together, making it an uncommon state of matter on Earth.

4. Which material has the smallest specific heat capacity?

A. water
B. wood
C. aluminum
D. glass

Correct answer: C

Rationale: Specific heat capacity is the amount of heat required to raise the temperature of a unit mass of a substance by one degree Celsius. Among the options provided, aluminum has the smallest specific heat capacity. This means that it requires the least amount of heat to raise its temperature compared to water, wood, and glass. Water has a high specific heat capacity, making it resistant to temperature changes, while wood and glass have higher specific heat capacities compared to aluminum.

5. Which of the following factors would not affect rates of reaction?

A. Temperature
B. Surface area
C. Pressure
D. Time

Correct answer: D

Rationale: Time would not directly affect rates of reaction. The rate of a chemical reaction is determined by factors that affect the frequency of successful collisions between reactant molecules, leading to a reaction. Temperature, surface area, and pressure can influence reaction rates by impacting the kinetic energy of molecules, the exposed surface for collisions, and the concentration of reactants, respectively. However, time, in the context of this question, does not alter the rate of reaction but may affect the extent of the reaction or the amount of product formed over time.